We all have our own karma and so different teachers will be meaningful to different students.
We have to know what is Buddhadharma and what is not Buddhadharma. It needn't go on forever. You don't have to spend 18 years at it. But still, a basic and uncompromised understanding of Buddhist principles is important. Very basic: the three signs of being, the four noble rruths, karma, and so on.
A realized being would not be making any fresh karma because karma is very much connected to the ego but would still be receiving the results of past karma.
